Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
bilateral, multilateral, unilateral (adjs.)
Bilateral means “two-sided, probably symmetrically so,” as in His hearing loss was bilateral; it involved both ears. Unilateral means “one-sided, involving only one party, independent,” as in She took unilateral action, not waiting to see whether her neighbors would decide to join her. Multilateral means “many-sided, involving many parties,” as in They finally all agreed to sign a very complex multilateral commercial treaty. All these words are Standard.
